JPH0768436B2 - Magnetic composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a magnetic material composition having excellent moldability, heat resistance, magnetic properties and mechanical properties.

<Prior Art> In recent years, plastic magnets made of a binder resin and a magnetic material that can be easily molded into a complicated shape have been developed in place of conventional sintered magnets. Demand for parts applications is increasing.

As the binder resin used, various types of elastomer, PVC, chlorinated polyethylene, EVA, nylon, PBT, P
There are thermoplastic resins such as PS and thermosetting resins such as epoxy resins. Among the performances of plastic magnets, heat resistance is mainly determined by this binder resin,
It is selected according to the end use and use conditions.

However, among the binder resins that have been conventionally used, thermosetting resins have problems in moldability, especially in mass productivity.

Thermoplastic binder resins are still insufficient for use in applications requiring heat resistance such as automobile applications. Among them PP
Although S has relatively high heat resistance, it has a problem of poor fluidity because of its high melt viscosity.

On the other hand, among thermoplastic resins, liquid crystal polyester exhibiting anisotropy when melted has been attracting attention because it exhibits excellent mechanical properties.

As this liquid crystal polymer, for example, a liquid crystal polyester obtained by copolymerizing polyethylene terephthalate with p-hydroxybenzoic acid is known (Japanese Patent Laid-Open No. 49-72393). However, this polymer does not have sufficient heat resistance.

Further, a method of copolymerizing p-hydroxybenzoic acid with 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid is disclosed in JP-B-57-24407 and JP-A-60-25046. It was found that the polymer thus obtained has high heat resistance, but has a high processing temperature, gas is generated during compounding and molding, and wettability with a magnetic material is poor.

JP-A-62-45660 discloses a composite material composition in which a liquid crystal polyester represented by p-hydroxybenzoic acid or 6-hydroxy-2-naphthoic acid type polyester is mixed with a magnetic powder and a surface treating agent. There is.

<Problems to be Solved by the Invention> However, since the composite material composition disclosed in the above-mentioned JP-A-62-45660 uses a surface treatment agent such as a coupling agent, heat resistance is deteriorated and at the time of molding. There are problems such as generation of dispersed gas. In addition, when a surface treatment agent such as a coupling agent is not used in combination, the fluidity deteriorates and
The mechanical properties and magnetic properties tended to deteriorate, which was not sufficient for practical use.

Therefore, it is an object of the present invention to obtain excellent heat resistance, moldability, mechanical properties, and magnetic properties of a binder resin and a magnetic powder without using a surface treatment agent such as a coupling agent. .

<Means for Solving Problems> The present inventors have arrived at the present invention as a result of extensive studies to solve the problems.

That is, the present invention comprises the following structural units (I) to (IV), a binder resin forming an anisotropic molten phase and a magnetic material, and the binder resin is 1 relative to the total amount of the binder resin and the magnetic powder. -99 wt% melt-moldable magnetic composition (However, X in the formula is And one or more groups selected from —CH ₂ CH ₂ —, wherein the structural unit (I) is 40 to 90 mol% of (I) + (II) + (III), and the structural unit [(II) + ( III)] is (I) + (II) +
Consists of 60 to 10 mol% of (III), and structural unit (II) / (I
When the molar ratio of (II) is 1/9 to 9/1 and X is —CH ₂ CH ₂ —, the molar ratio of structural units (II) / (III) is 86/14 to 95/5,
It is preferably 88/12 to 93/7, and the structural unit (III) is 5 to 23 mol% of (I) + (II) + (III). The carbonyl groups in the dicarboxylic acid component in (IV) are in a meta and / or para relationship with each other, and 65 mol% or more is in the para position. In addition, structural unit [(II) + (III)]
And (IV) are substantially equimolar. ) And (A) p-hydroxybenzoic acid, (B) 4,4′-
Dihydroxybiphenyl, (C) terephthalic acid and /
Alternatively, a magnetic material comprising a binder resin composed of the following structural units (I) to (IV) and a magnetic substance, which is produced by acylating a hydroxyl group of a raw material composed of isophthalic acid and (D) polyethylene terephthalate with acetic anhydride and deacetic acid polymerization It relates to a body composition.

In the binder resin used in the present invention, the structural unit (I) represents a structural unit formed from p-vidroxybenzoic acid.

Structural unit (II) is a structural unit formed from 4,4′-dihydroxybiphenyl, structural unit (III) is hydroquinone, t-butylhydroquinone, 4,4′-dihydroxydiphenyl ether, 2,6-dihydroxynaphthalene,
2,7-dihydroxynaphthalene, chlorohydroquinone, methylhydroquinone, phenylhydroquinone,
A structural unit formed from one or more dihydroxy compounds selected from ethylene glycol, preferably one or more dihydroxy compounds selected from hydroquinone, t-butylhydroquinone, phenylhydroquinone and ethylene glycol, wherein structural unit (IV) is terephthalate A structural unit formed from an acid and / or isophthalic acid is shown.

The structural unit (I) is 40 to 9 of (I) + (II) + (III).
It is essential that the content is 0 mol%, preferably 60 to 85 mol%, and the structural unit (I) is (I) + (II) + (II
If it exceeds 90 mol% or less than 40 mol% of I), the fluidity is poor and it is not practical.

On the other hand, the molar ratio of the structural unit (II) / (III) is 9/1 to 1 /
A 9, X is -CH ₂ CH ₂ - otherwise preferably 7.5 /
2.5 to 4/6. If it exceeds 9/1 or is less than 1/9, the fluidity is still poor and it is not practical.

The dicarboxylic acid component of structural formula (IV) is terephthalic acid and / or isophthalic acid,
The molar ratio of isophthalic acid is 10/0 to 6.5 / 3.5. That is, 65 mol% or more of the dicarboxylic acid component in the structural unit (IV) is terephthalic acid.

The binder resin used in the present invention can be produced according to a conventional polyester polycondensation method, and is not particularly limited,
Typical production methods include the following methods (1) to (4) in the presence or absence of polyethylene terephthalate, and the method (2) is particularly preferable in the presence of polyethylene terephthalate.

(1) Acylated product of p-acetoxybenzoic acid, 4,4′-
A method for producing an acylated product of an aromatic hydroxy compound such as diacetoxybiphenyl and an aromatic dicarboxylic acid such as terephthalic acid by a deacetic acid polycondensation reaction.

(2) A method of producing by a deacetic acid polycondensation reaction from an aromatic dihydroxy compound such as p-hydroxybenzoic acid or 4,4'-dihydroxybiphenyl, an aromatic dicarboxylic acid such as terephthalic acid and acetic anhydride.

(3) A method for producing from a phenyl ester of p-hydroxybenzoic acid and an aromatic dihydroxy compound such as 4,4'-dihydroxybiphenyl and a diphenyl ester of an aromatic dicarboxylic acid such as terephthalic acid by dephenol polycondensation.

(4) After reacting aromatic dicarboxylic acids such as p-hydroxybenzoic acid and terephthalic acid with desired amounts of diphenyl carbonate to form diphenyl esters,
A method in which an aromatic dihydroxy compound such as 4,4'-dihydroxybiphenyl is added to produce by a dephenol polycondensation reaction.

Typical catalysts used in the polycondensation reaction are metal compounds such as stannous acetate, tetrabutyl titanate, lead acetate, antimony trioxide, magnesium, sodium acetate, potassium acetate and trisodium phosphate, especially dephenolized. Effective during polycondensation.

The binder resin used in the present invention forms an anisotropic molten phase, but was measured at a shearing rate of 1,000 (1 / sec) at a temperature 40 ° C. higher than the temperature at which anisotropy starts (liquid crystal starting temperature). Those having a melt viscosity of 10 to 15,000 poise can be preferably used.

Incidentally, with respect to the binder resin of the present invention, glass fiber, carbon fiber, reinforcing agents such as asbestos, fillers, nucleating agents, pigments, antioxidants, stabilizers, lubricants, mold release within the range not impairing the object of the present invention. Additives such as agents and flame retardants and other thermoplastic resins can be added to impart desired properties to the molded article.

On the other hand, as the magnetic powder used in the composition of the present invention, those usually used in plastic resins can be used.

For example, ferrite-based magnetic powder represented by strontium ferrite, rare earth Sm-Co powder, Nd-Fe-B powder and the like can be mentioned. The average particle size of magnetic powder is 0.5 to 200
Those in the range of μ can be preferably used.

The magnetic powder of the present invention can be obtained by kneading the binder resin and the magnetic powder. The kneading method is not limited, but at a temperature equal to or higher than the liquid crystal starting temperature of the binder resin,
It can be performed using a device such as a single-screw extruder, a twin-screw extruder, or a kneader.

The magnetic material composition of the present invention becomes a isotropic magnet by magnetizing after molding. However, a magnetic field orientation molding method in which a magnetic field is generated and magnetized in the mold during molding can be preferably used.

Thus, the magnetic composition of the present invention has excellent moldability,
The plastic magnet obtained by molding has excellent heat resistance and excellent mechanical and magnetic properties.

<Example> Hereinafter, the present invention will be described in more detail with reference to Examples.

Reference Example 1 519 parts by weight of p-acetoxybenzoic acid, 184 parts by weight of 4,4'-diacetoxybiphenyl, 85 parts by weight of t-butyl hydroquinone diacetate, 19.4 of hydroquinone diacetate.
186 parts by weight of terephthalic acid and 100 parts by weight of terephthalic acid were charged into a reaction vessel equipped with a stirring blade and a distilling tube, and heated to 250 in a nitrogen gas atmosphere.
After reacting at ~ 340 ℃ for 3.0 hours, heated to 350 ℃ and then 1.5mmHg
The system was depressurized and heated for an additional 1.0 hour to carry out a polycondensation reaction to obtain a resin A having the following theoretical structural formula.

l / m / n / o / = 72/17 / 8.5 / 2.5 Moreover, when this resin A was placed on the sample stage of a polarizing microscope and the temperature was raised to check the optical anisotropy, it was good at 307 ° C or higher. It showed excellent optical anisotropy.

Reference Example 2 541 parts by weight of p-acetoxybenzoic acid, 184 parts by weight of 4,4'-diacetoxybiphenyl, hydroquinone diacetate 6
2 parts by weight and 124 parts by weight terephthalic acid, 42 isophthalic acid
Part by weight was charged into a reaction vessel equipped with a stirring blade and a distillation tube, reacted at 250 to 360 ° C under a nitrogen gas atmosphere for 3 hours, and then 1 m.
The pressure was reduced to mHg, and the mixture was further heated for 1 hour to complete polycondensation to obtain a resin B having the following logical structural formula.

l / m / n = 75 / 18.75 / 6.25 When this polyester was placed on a sample stage of a polarization microscope and heated to recognize the optical anisotropy, good optical anisotropy was shown at 305 ° C or higher.

Reference Example 3 608 parts by weight of p-acetoxybenzoic acid, 122 parts by weight of 4,4′-diacetoxybiphenyl, 75 parts by weight of terephthalic acid and 130 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 are equipped with a stirring blade and a distillation pipe. The reaction vessel was charged to carry out deacetic acid polymerization.

First, after reacting in a nitrogen gas atmosphere at 250 to 300 ° C. for 2.5 hours, the pressure was reduced to 0.2 mmHg at 300 ° C., and the reaction was continued for 3.25 hours to complete the polycondensation. Resin C having the following theoretical structural formula was obtained.

l / m / n = 75/10/15 Also, the polyester was placed on the sample stage of a polarization microscope and the temperature was raised to confirm the optical anisotropy.
The temperature was 264 ° C., indicating good optical anisotropy.

Reference Example 4 466 parts by weight of p-hydroxybenzoic acid, 84 parts by weight of 4,4'-dihydroxybiphenyl, 75 parts by weight of terephthalic acid and 130 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 and 480 parts by weight of acetic anhydride were stirred, After being charged into a reaction vessel equipped with a distillation tube for acylation, deacetic acid polymerization was carried out.

First, a reaction was carried out at 100 to 250 ° C. for 5 hours in a nitrogen gas atmosphere, and then polycondensation was carried out in the same manner as in Reference Example 3 to obtain a resin C ′ having the same structural formula as in Reference Example 3.

Examples 1 to 5 Samarium cobalt powder having an average particle diameter of 6 μm and Reference Examples 1 to 3
The resins A, B, and C obtained in 1. above were used as binder resins in the proportions shown in Table 1 and were extruded and pelletized. A magnetic field of 15 KOe was generated in the mold for the pellets, magnetic field orientation molding was carried out to obtain a disk-shaped molded product, and the magnetic properties of this molded product were measured. In addition, Izod impact test pieces and 3 mm thick bending test pieces were molded without applying a magnetic field, and various mechanical properties were measured.

Example 6 A molded product was obtained and measured in the same manner as in Example 1 except that strontium ferrite powder having an average particle diameter of 1.4 μ was used. The results are shown in Table 2.

Comparative Examples 1 to 3 The same magnetic powder used in Examples and resins D to F represented by the following theoretical structural formulas were blended at a ratio shown in Table 1 and extruded to obtain molded articles similar to those in Examples. Was prepared and the magnetic properties and mechanical properties were measured. The results are shown in Table 2.

As shown in Table 2, the magnetic composition according to the present invention is superior to the compositions shown in Comparative Examples in all of the mechanical properties represented by impact strength, heat resistance, and magnetic properties.

Example 7 In place of Example 5, the resin C ′ of Reference Example 4 is used, and Example 5 is used.
When the same experiment was performed, the impact strength was 5.1 kgcm / cm,
Heat distortion temperature 250 ℃, residual magnetic flux density 7070G, coercive force 7050Oe,
The maximum energy product was 8.4 MG · Oe.

<Effects of the Invention> The magnetic composition of the present invention makes it possible to obtain a plastic magnet having excellent heat resistance, mechanical properties and magnetic properties.

Claims (2)

[Claims] 1. A binder resin comprising the following structural units (I) to (IV) and forming an anisotropic molten phase, and a magnetic substance, wherein the binder resin is 1 relative to the total amount of the binder resin and the magnetic substance powder. Melt-moldable magnetic material composition of about 99% by weight. (However, X in the formula is And --CH ₂ CH _2- , one or more groups selected from the group consisting of structural units (I) of [(I) + (II) + (III)] 40-90
Mol%, structural unit [(II) + (III)] is [(I) + (I
I) + (III)], and the structural unit (I
The molar ratio of (I) / (III) is 1/9 to 9/1, and X is —CH ₂ CH ₂
In the case of −, the structural unit (III) is [(I) + (II) +
(III)]. The structural unit (I
The carbonyl groups in the dicarboxylic acid component of V) are in a meta and / or para relationship with each other, and 65 mol% or more is in the para position. In addition, structural units [(II) + (III)] and (IV)
And are substantially equimolar. ) 2. (A) p-hydroxybenzoic acid, (B) 4,
Structural units (I) to The magnetic substance composition according to claim 1, which comprises a binder resin comprising (IV) and a magnetic substance. (However, the structural unit (I) is [(I) + (II) + (II
40 to 90 mol% of the structural unit (II) is [(I) + (I
I) + (III)], and the structural unit (II)
The molar ratio of / (III) is 1/9 to 9/1, and the structural unit (III)
Is 5 to 23 mol% of [(I) + (II) + (III)]. Further, the structural units [(II) + (III)] and (IV) are substantially equimolar, and the carbonyl groups of the structural unit (IV) are in a meta and / or para relationship with each other, and 65 mol%
The above is para. )